PCA (preconditioned air) ducting is required to connect GSE (ground service equipment) that supplies cooled, heated and dehumidified air to the aircraft while parked at the terminal. It is important that the PCA ducting be properly insulated to ensure comfortable temperatures and environment for passengers and crew while at the gate.
GSE with PCA ducting often replaces the aircraft’s own auxiliary power unit because it is more efficient, doesn’t burn expensive jet fuel and cuts down on exhaust emissions. PCA ducting is used in both military and civilian applications.